The only problem I have had with RPGNow is that big-name publishers don't release things through them. The stuff there is excellent, but it's a big stretch of small-press or "indie" (whatever that means) games with no real big-name punch for people that are looking for books from companies they know. That's not RPGNow's fault, just the way things seem to the outside purchaser.
Steve Jackson Games has entered the digital publishing arena, and has taken far more lessons from RPGNow than anywhere else. They've got it right, when it comes to customer-vs-criminal. Looks like I can finally get those GURPS books I've been unable to find.
: I run Linux. I cannot open DRM-encoded e-books without violating all manner of dumb laws (DMCA, anyone?), even if I have paid for them.